/Engine/Plugins/Online/OnlineServices/Source/OnlineServicesCommon/Public/Online/LobbiesCommon.h
Change the join policy applied to the lobby. Only the lobby leader may change the join policy.
virtual [TOnlineAsyncOpHandle](API\Plugins\OnlineServicesInterface\Online\TOnlineAsyncOpHandle)< [FModifyLobbyJoinPolicy](API\Plugins\OnlineServicesInterface\Online\FModifyLobbyJoinPolicy) > ModifyLobbyJoinPolicy ( [FModifyLobbyJoinPolicy::Params](API\Plugins\OnlineServicesInterface\Online\FModifyLobbyJoinPolicy\Params) && Params )